The invention relates to a work chamber system for the surface treatment of workpieces, comprising at least:
At least one tightly closable work chamber,
At least one frame-like workpiece holder that can be moved on a guide rail between an assembly position outside the work chamber and a work position inside the work chamber,
One manipulator that, when seen in plan view, is arranged next to a group of parallel guide rails inside the work chamber.
Certain types of workpiece surface treatments must be carried out in enclosed work chambers, for example painting or treatments with abrasive blasting agents. The treatment itself is carried out by program-controlled manipulators. Due to the high operating speed of the manipulators, the cycle times are not determined by the actual treatment time, but essentially by the placement of the workpieces in the work chamber and the mounting therein.
To reduce cycle times and to achieve high system throughput, a work chamber system of the kind mentioned above and offered for sale by the applicant provides for the workpieces to be mounted in workpiece holders that are already outside the work chamber. The surface treatment in the work chamber must be interrupted only briefly to move one of the rail-guided workpiece holders with the fully treated workpieces out of the work chamber, and to bring the other workpiece holder with the prepared workpieces into it. At their respective end sides, the workpiece holders have seal plates that tightly close the passages in the work chamber as soon as a workpiece holder has arrived either in the assembly position outside the chamber or in the work position inside the chamber.
This work chamber system has basically proven itself. However, one disadvantage arises in that the workpiece holders are guided on parallel rails, with one of the rails necessarily positioned closer to the manipulator than the other. Thus, there are different distances between the manipulator head with the paint or spray nozzles and the workpieces, depending on which one of the workpiece holders happens to be in the work chamber, such that the result of the work may turn out differently as well.
Although the problem can often be solved by two guide rails in that the manipulators are used in pairs, which are each arranged on one side of the group of adjacent guide rails and work in opposite directions. These then process the front and the rear side of the workpieces alternately. However, this entails a higher cost investment.
If the manipulator is mounted stationary and has as a first axis a rotation axis without being longitudinally movable along the guide rails, then difficulties can arise for it to reach the outer areas of the work area as defined by the outer frame of the workplace holder, especially if there is a greater distance to the workpiece holder.
More than two workpiece holders are required if the cycle times of the surface treatment, as compared to the set-up times for removing and mounting of workpieces, are very short. In this case, mounting is separated from removing by using a total of three workpiece holders: A first one for mounting the raw workpieces, a second for processing in the chamber and a third for removing the finished treated workpieces outside the chamber. In this configuration, the disadvantages mentioned remain, even when using a pair of manipulators on opposite sides, because than even twice as large a distance exists between the respective outer guide rails than between two directly adjacent guide rails. Especially in tight work chambers and when using 6-axis articulated robots with their limited working space as manipulators, not all points of the work surface can be reached inside the workpiece holder, at least not at the right distance and in the required orientation of the manipulator head.
Known from U.S. Pat. No. 3,149,445 is a working chamber system with an outer frame guided on rails and being used to transfer work pieces individually or in transport boxes into the processing position.
However, this rail-like arrangement requires a large width and does not allow for prepared mounting of a workpiece in a defined position that then only needs to be moved into the work chamber.
Known from DE 27 47 107 A1 is a work chamber system, wherein the workpieces can be transferred to the processing position individually or on pallets via a roller conveyor and can be positioned inside the work chamber via a turntable. However, a frame-like arrangement, that allows the upright mounting of workpieces such that they can be placed frontally in the workspace of a manipulator, does not exist.